Abrasive member for dry grinding and polishing

ABSTRACT

A flexible abrasive member comprising a first porous layer of mesh, non-woven or perforated sheet, conductive or non-conductive material to which on one side deposits are deposited by way of any metal plating technique of either the electrolytic, electroless or vacuum deposition type, or any galvanic process, abrasive particles being embedded in the metal deposits, a layer of filling material, such as a resin, being present between the deposits which filling material is bonded to said first porous layer and/or the deposits, and at least a second porous layer of mesh, non-woven or perforated sheet, conductive or non-conductive material being present and being laid substantially along one side of the first porous layer. The side edge of the deposit has at least one annular groove along at least part of the circumference of the deposit.

FIELD OF THE INVENTION

The present invention relates to a flexible abrasive member comprising afirst porous layer of, for example, mesh, non-woven or perforated sheet,conductive or non-conductive material to which at one side deposits aredeposited by way of any metal plating technique of either theelectrolytic, electroless or vacuum deposition type, or any galvanicprocess, abrasive particles being embedded in the metal deposits, alayer of filling material, such as a resin, being present between thedeposits which filling material is bonded to said first porous layerand/or the deposits, and at least a second porous layer of, for example,mesh, non-woven or perforated sheet, conductive or non-conductivematerial being present and being laid substantially along one side ofsaid first porous layer.

BACKGROUND OF THE INVENTION

Abrasive members for grinding and polishing are well known in the art.Two types of such abrasive members are known. Firstly the type for drygrinding and polishing comprising for example silicon carbide oraluminium/oxide, having a short life time. Secondly the type for wetgrinding and polishing comprising diamond particles as abrasiveparticles, which type may only be applied using a coolant, by examplewater. When this second type of abrasive member is used for dry grindingand polishing the life time is very short. In some applications it isdesired to use an abrasive member with diamond particles when coolantmay affect the product to be ground or polished or any object nearby,whereby using coolant is not allowed. At presently there are no abrasivemembers well suited for these applications. The significantcharacteristic of an abrasive member is its resistant to wear due tothermal effects and mechanical effects.

In practice the problems to increase the life time of the abrasivemember are that flexibility of the abrasive member must be maintained,that moldable materials having a high specific heat conductive capacityare known to have generally bad characteristics concerning resistance towear due to mechanical effects, that a very strong bonding between allmaterials in the composition of the abrasive member, in particularbetween the abrasive particles and the backing material of the abrasivemember, must be achieved, and that it must be possible to produce thiscomposition easily and with low production cost.

OBJECT OF THE INVENTION

The object of the invention is to provide a flexible abrasive memberwith diamond particles for dry grinding and polishing with a highmechanical and thermal resistance to wear so that a much longer lifetimeis achieved than can be achieved by the conventional flexible, diamondabrasive members.

SUMMARY OF THE INVENTION

This object of the invention is achieved by the side edge of the deposithaving at least one annular groove along at least part of thecircumference of the deposit. The layer of filling material may extendsubstantially into and at least along part of this annular groove.Hereby part of said layer is encapsulated by the groove thus increasingresistance to mechanical wear and tear. The abrasive member isreinforced by the second porous layer whereby its mechanical resistanceis increased, while its flexibility is maintained. Moreover its thermalresistance is increased for the amount of heat conducting material isincreased by applying the other layer.

According to another aspect of the invention the annular groove isachieved by any metal plating technique of either the electrolytic,electroless or vacuum deposition type, or any galvanic process.Generally a groove may be achieved by known methods. Obviously a grooveper deposit in the side edge of a deposit having micro to millidimensions, while hundreds to thousands of deposits are present perabrasive member, is hard to achieve. By the method according to thepresent invention such a groove is easily achieved using the sametechnique that creates the deposit itself.

According to another aspect of the invention the layer of fillingmaterial consists of material having a heat resistant pointsubstantially less than or about 200° C. Herein the heat resistant pointis the temperature above which the material fails, i.e. melts andthereby deforms and affects the abrasive member in its functioning.Material having a higher heat resistant point is a much complexer typeof material and in practice is much more expensive than a materialhaving a said heat resistant point. The filling material may bepolyurethane, acrylicacetate or epoxyresin.

According to another aspect of the invention a following porous layer atleast partially is interwoven or spot welded with at least one of thepreceding porous layers. The present invention can be practiced wheneither two or more porous layers are laid on top of each other or two ormore porous layers are interconnected to each other, for example bybeing interwoven or spot welded with each other. Just the presence oftwo or more layers or interstices between two or more mesh, non-woven orperforated sheet materials is important so as to enable the depositionof a deposit having an annular groove, which groove is for exampleachieved by embedding these two or more layers in the deposit. At leastthe second porous layer may at least partially be interwoven or spotwelded with the first porous layer.

According to another aspect of the invention the first porous layer withlow mesh count or open structure faces the anode and the second porouslayer with high mesh count or dense structure faces the cathode. Herebyelectrodeposition of metal onto both layers is improved because thestraight line between anode and cathode is less or hardly interferredwith by any object, while a greater surface of the cathode is exposed tothe electrodeposition bath.

According to another aspect of the invention the mesh count of thesecond porous layer is 2.5 to 6 times higher than the mesh count of thefirst porous layer. In practice this range gives the best results.

According to another aspect of the invention a layer of any resinmaterial, such as any glue material, extends along one side of the firstporous layer and substantially between all deposits. This resin materialmay be used for filling the remaining space between deposit, layer offilling material and the second porous layer, thus reinforcing theabrasive member and thus increasing the resistance to wear. Moreover,the glue material may be used to attach the abrasive member to thebacking layer mentioned above, thus also increasing the resistance towear. Herein the layer of resin material embeds at least part of thesecond porous layer thus causing a better bonding effect. This layer ofresin material may be bonded to the second porous layer and/or the layerof filling material and/or the deposits.

In general terms, the object of the present invention is achieved byenlarging the heat conductive capacity of the abrasive member andreinforcing the bonding of the several materials to each other.

The heat conductive capacity is enlarged firstly by increasing the massof the abrasive member without loosing the flexibility required andsecondly by using filling material with a higher specific heatconductive capacity, which material has not yet been used in long lifetime abrasive members for dry grinding or polishing, because of itsreally bad bonding characteristics.

Increasing the mass of the abrasive member is achieved basically byapplying more material. Increasing the mass of the abrasive memberincreases the amount of heat leaking away per time unit so that moreheat may be fed to the abrasive member by dry grinding or polishing onthe spot. It is important not to lose any flexibility of the abrasivemember so a flexible filling material is applied just as is in the wellknown abrasive members.

Using filling material with a higher specific heat conductive capacity,naturally increases the amount of heat leaking away per time unit orbeing absorbed. A larger heat conductive capacity increases theresistance to wear of the abrasive member.

The bonding of the several materials to each other is reinforced firstlyby providing a deposit with a substantially U-shaped side profile insectional view, secondly for providing a second porous layer of, byexample, mesh, non-woven or perforated sheet material along the firstporous layer of, for example, mesh, non-woven or perforated sheetmaterial, which second porous layer has a higher mesh count or a moreopen structure than the first porous layer, and thirdly by applying glueto the portions where no deposits are present in the second porouslayer.

The substantially U-shaped side profile in sectional view of the depositencapsulates part of the filling material applied to the portions of thefirst porous layer where no deposits are present. Hereby a mechanicalenclosure is achieved rather than a chemical bonding of the fillingmaterial to the deposit material, which mechanical enclosure has ahigher resistance to wear than this chemical bonding.

The second porous layer laid on the well known first porous layerprovides per deposit a larger surface for attaching the depositmaterial. Moreover, tearing of the abrasive member is rendered moredifficult because more attachements per deposit have to be torn whilenaturally tearing two layers of, for example, mesh, non-woven orperforated sheet materials at one time is more difficult than tearingonly one such layer.

The mesh count or density of the second porous layer of, for example,mesh, non-woven or perforated sheet material is higher than that of thefirst porous layer for convenience of depositing in a galvanic process.Any relation may be provided between the grade of the first relative tothe second porous layer, although in practice the best results have beenachieved using a relation not equal to one, in particular less than one.The better the depositing takes place the mope the mechanical resistanceto wear of the abrasive member is increased.

Applying glue to the portions where no deposits are present in thesecond porous layer reinforces chemically the bonding between fillingmaterial, deposit and both porous layers, while the flexibility of theabrasive member is not decreased. Hereby the resistance to mechanicallycaused wear of the abrasive member is increased.

When one of the porous layers is made of conductive material, this layeritself may form the cathode in the electrolytic process. Thereby aseparate cathode may be omitted. This layer will then be indicated asbeing a `permanent cathode`.

Several methods of making abrasive members are well known in the art.The methods known, are not suited for making the abrasive member of thepresent invention because no annular groove in the side edge of thedeposits may be achieved by way of any metal plating technique known ofeither the electrolytic, electroless or vacuum deposition type, or anygalvanic process.

One method for producing a flexible abrasive member according to thepresent invention comprises the steps of applying said first porouslayer of, for example, mesh, non-woven or perforated sheet, conductiveor non-conductive material with electrically insulating material, i.e.said layer of filling material, over selected areas so that the metallayer is deposited only over the remaining non-covered discrete areas ofthe surface of said first porous layer, connecting said first porouslayer to a cathode, by example a metal face which forms the cathode inthe electrolytic process, electrolytically depositing metal through thepores or interstices of said first porous layer causing a firm bondbetween the metal deposits thus built up and the first porous layerpreferably in the presence of abrasive material, continuing theelectrolytical deposition until metal has been deposited beyond theheight of the layer of filling material above the top surface of thecathode, causing the creation of a radially extending annular rim,turning the first porous layer including the layer of filling materialand the deposits up side down the deposits created now forming thecathode in the electrolytic process, laying a second porous layer of, byexample, mesh, non-woven or perforated sheet, conductive ornon-conductive material onto the free surface of the first porous layer,restarting the electrolytic process causing metal to be depositedthrough the pores or interstices of the second porous layer embedding atleast part of the second porous layer by creating relative to a depositcreated earlier a radially extending annular rim. By this method anabrasive member is achieved having an annular groove along thecircumference of the deposit. This groove is substantially filled withmaterial of the layer of filling material so that this layer isencapsulated by the groove. Hereby a mechanical enclosure is achieved,which causes a high resistance to wear.

To improve the high resistance to mechanical wear of the first methodmentioned above, another method comprises the step of putting the membercreated into a reactivation bath before the step (see method mentionedabove) of laying the second porous layer onto the free surface of thefirst porous layer, for working the surfaces of the deposits created,which surfaces lie on the surface of the cathode, so as to prepare saidsurfaces for extended metal deposition onto these surfaces. Working thesurfaces of the deposits affects the surface structure of the depositalready formed whereby a much better coalescence between the extendedmetal deposit and said surface structure is achieved.

Another method comprises the steps of applying the first porous layerwith the second porous layer, laying both the first and the secondporous layer as one composition onto a metal face, which forms thecathode in the electrolytic process, applying said composition of layerswith electrically insulating material, i.e. said layer of fillingmaterial, over selected areas so that the metal layer is deposited onlyover the remaining non-covered discrete areas of the surface of thecomposition of layers, electrolytically depositing metal through thepores or interstices of the layers of the composition causing a firmbond between the metal deposits thus built up and the porous layerspreferably in the presence of abrasive material, continuing theelectrolytical deposition until metal has been deposited beyond theheight of the layer of filling material above the top surface of thecathode, causing the creation of a radial extending annular rim. Thismethod based upon the same idea of the two methods mentioned above iseasier to perform than those two methods, but a less clear groove isachieved. Nevertheless, this method provides a good compromise for easeof production, and thereby cost of production, sad resistance tomechanical tear.

The composition of layers may be formed by two or more at leastpartially interwoven or spot welded porous layers of, by example, mesh,non-woven or perforated sheet material, whereby in the preceding methodthe first step of applying the first porous layer with the second porouslayer may be omitted or this first porous layer may be formed by saidcomposition of layers. As was mentioned above the present invention canbe practiced when either two or more porous layers are laid on top ofeach other or two or more porous layers are interconnected to eachother, for example by being interwoven or spot welded with each other.When using a material consisting of two or more interwoven or spotwelded layers of porous material the present invention may be producedby using a even easier method.

According to another aspect of the invention at least one side of themember created may be applied with a layer of resin, such as a gluematerial, for example epoxy, polyester or polyurethane. Hereby themember may be attached to a backing layer thereby reinforcing theabrasive member and causing higher resistance to wear due to mechanicalor thermal influences.

According to another aspect of the invention the electrically insulatingmaterial, i.e. said layer of filling material, may be applied by way ofproducing of a printing image including the steps of applying aphotographic resist onto the surface of the first porous layer, exposingthe resist to a film having the desired copy, development of the imagethereby leaving a resist pattern, and etching of the surface to removethe resist material around the resist pattern thereby opening the firstporous layer where the resist material is removed to define an etchedimage on the surface. Although this method is well known in screenprinting techniques, and in providing a mask as part of a metaldeposition process, it has not yet been used to provide the fillinglayer. The possibility to use a filling material having a much lowerheat resistance enables the use of less complex material whereby screenprint techniques may be employed.

According to another aspect of the invention the second porous layer isan electrically conductive material. Hereby metal is deposited ontosections of this second porous layer also resulting in better bonding byembedding whereby the resistance to mechanical wear is increased.

According to another aspect of the invention one side of the membercreated is applied with a backing layer, the bonding between saidbacking layer and the member created being achieved by the layer of gluematerial being applied earlier. As was mentioned before, a backing layermay reinforce the abrasive member and thus causes higher resistance towear due to mechanical or thermal influences.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be further elucidated referring to two embodiments ofthe invention shown in the drawing, wherein:

FIG. 1 shows the result of the first four steps of one method forproducing a flexible abrasive member according to the present invention;

FIG. 2 shows the result of the rest of the steps of the first methodand;

FIG. 3 shows the result of the steps of another method for producing aflexible abrasive member according to the present invention.

In FIG. 1 a first embodiment of the abrasive member according to theinvention is shown. The flexible abrasive member comprises a firstporous layer 1 of, for example, mesh, non-woven or perforated sheetmaterial to which on one side deposits 2 are deposited by way of anymetal plating technique of either the electrolytic, electroless orvacuum deposition type, or any galvanic process, abrasive particles 3being embedded in the metal deposits 2, and a layer 4 of fillingmaterial, such as a resin, being present between the deposits 2, whichfilling material 4 is bonded to the first porous layer 1 and/or thedeposits 2. The flexible abrasive member is made by firstly laying thefirst porous layer 1 onto a metal surface 9, which forms the cathode inthe electrolytic process. Secondly the first porous layer i is appliedwith electrically insulating material, i.e. the layer 4 of fillingmaterial, over selected areas so that the metal layer is deposited onlyover the remaining non-covered discrete areas of the surface of thefirst porous layer. Thirdly metal 2 is electrolytically depositedthrough the pores or interstices of the first porous layer 1 causing afirm bond between the metal deposits 2 thus built up and the firstporous layer 1. Preferably this is done in the presence of abrasivematerial 3 so that this material becomes imbedded in the deposits.Further the electrolytical deposition is continued until metal has beendeposited beyond the height of the layer 4 of filling material above thetop surface of the cathode 9, causing the creation of a radial extendingannular rim 10. Then the member thus created, including the first porouslayer 1, the layer 4 of filling material and the deposits 2, is takenoff the surface 9 and is turned up side down for continuation of theproduction process.

In FIG. 2 the result of the extended metal electrodeposition to theabrasive member according to FIG. 1 is shown. Said production process iscontinued wherein the member turned up side down now forms the cathodein the electrolytic process. The following steps of the method arefirstly laying a second porous layer 5 of, by example, mesh, non-wovenor perforated sheet material onto the free surface of the first porouslayer 1 and secondly restarting the electrolytic process causing metal12 to be deposited through the pores or interstices of said secondporous layer 5 embedding at least part of said second porous layer 5 bycreating relative to a deposit 2 created earlier a radially extendingannular rim 11. Finally the abrasive member comprises a second porouslayer 5 of mesh or non-woven conductive or non-conductive material laidsubstantially along one side of said first porous layer 1.

As can be seen from FIGS. 2 and 3 the mesh count of the second porouslayer 5 is higher than the mesh count of the first porous layer 1.

By the invention, in the side edge 6 of the deposit 2 at least oneannular groove 7 along at least part of the circumference of the deposit2 has been formed. The layer 4 of filling material extends substantiallyinto and at least along part of this annular groove 7. The layer 4 offilling material extends substantially between all deposits 2, and alayer 8 of a glue material, extends along one side of the first porouslayer 1 and substantially between all deposits 2. A backing layer 14 isattached via the glue layer 8 to the abrasive member. The layer 8 embedsat least part of said second porous layer 5.

After turning the abrasive member created so as to continue metalelectrodeposition a dividing line 15 is formed between the deposit 2which has been created already and the extended deposit 12 which now hasto be created. To improve the high resistance to mechanical wear themember created may be put into a reactivation bath before the step oflaying the second porous layer 5 onto the free surface of the firstporous layer 1, for working the surfaces of the deposits created. Thisis done to affect the surface structure of the deposits 2 already formedwhereby a much better coalescense between the extended metal deposit 12and the surface structure 2 is achieved.

In FIG. 3 another embodiment of the abrasive member according to theinvention is shown. The flexible abrasive member comprises a firstporous layer 1 to which on one side deposits 2 are deposited by way ofany metal plating technique of either the electrolytic, electroless orvacuum deposition type, or any galvanic process, abrasive particlesbeing embedded in the metal deposits 2, and a layer 4 of fillingmaterial, such as a resin, being present between the deposits 2, whichfilling material 4 is bonded to the first porous layer 1 and/or thedeposits 2. Further the abrasive member comprises a second porous layer5 of mesh or non-woven conductive or non-conductive material laidsubstantially along one side of said first porous layer 1, and a layer 8of a glue material, extending along one side of the first porous layer 1and substantially between all deposits 2 embedding at least part of thesecond porous layer 5.

This flexible abrasive member is made by firstly applying to the firstporous layer the second porous layer 5. Secondly both said first 1 andsaid second porous layer 5 are laid as one composition onto a metalsurface 9, which forms the cathode in the electrolytic process. Thirdlythis composition of layers is covered with electrically insulatingmaterial, i.e. the layer 4 of filling material, over selected areas sothat the metal layer 2 is deposited only over the remaining non-covereddiscrete areas of the surface of the composition of layers. Furthermetal is electrolytically deposited through the pores or interstices ofthe layers of the composition causing a firm bond between the metaldeposits 2 thus built up and the porous layers. Preferably this is donein the presence of abrasive material 3 so that this material 3 becomesembedded in the deposits 2. Finally electrolytical deposition iscontinued until metal 2 has been deposited beyond the height of thelayer 4 of filling material above the top surface of said cathode (notshown), causing the creation of a radially extending annular rim 10.

By way of this method, in the side edge 6 of the deposit 2 an annulargroove 7 along at least part of the circumference of the deposit 2 hasbeen formed. Relative to the groove 7 in the deposits according to FIG.2 now a less clear groove 7 is achieved, mainly because rim 13 is quitea bit smaller than rim 11. Nevertheless the layer 4 of filling materialextends substantially into and at least along part of this annulargroove 7 thus being encapsulated by the rims 10 and 13 and the deposit2. The layer 4 of filling material extends substantially between alldeposits 2, and a layer 8 of a glue material, extends along one side ofthe first porous layer 1 and substantially between all deposits 2.

I claim:
 1. A flexible abrasive member comprising a first porous layer(1) of mesh, non-woven or perforated sheet material to which at one sidemetal deposits (2) are deposited, abrasive particles (3) being embeddedin the metal deposits (2), a layer (4) of filling material being presentbetween the metal deposits (2) which filling material (4) is bonded toat least one of said first porous layer (1) and the metal deposits (2),and at least a second porous layer (5) of mesh, non-woven or perforatedsheet material being present and being laid substantially along one sideof said first porous layer (1), the side edge (6) of said metal deposits(2) having at least one annular groove (7) along at least part of thecircumference of said metal deposits (2).
 2. A flexible abrasive memberaccording to claim 1, wherein said layer (4) of filling material extendssubstantially into and at least along part of said annular groove (7).3. A flexible abrasive member according to claim 1, wherein said layer(4) of filling material consists of material having a heat resistantpoint no greater than about 200° C.
 4. A flexible abrasive memberaccording to claim 3, wherein said filling material is polyurethaneacrylic acetate or epoxy resin.
 5. A flexible abrasive member accordingto claim 1, wherein a following porous layer at least partially isinterwoven or spot welded with at least one of the preceding porouslayers.
 6. A flexible abrasive member according to claim 5, wherein thesecond porous layer (2) at least partially is interwoven or spot weldedwith the first porous layer (1).
 7. A flexible abrasive member accordingto claim 1, wherein the first porous layer (1) has a lower mesh countand the second porous layer (5) has a higher mesh count.
 8. A flexibleabrasive member according to claim 7, wherein the mesh count of saidsecond porous layer (5) is 2.5 to 6 times the mesh count of said firstporous layer (1).
 9. A flexible abrasive member according to claim 1,wherein said layer (4) of filling material extends substantially betweenall deposits (2), and further comprising a layer (8) of glue materialthat extends along one side of said first porous layer (1) andsubstantially between all said deposits (2).
 10. A flexible abrasivemember according to claim 9, wherein said layer (8) of glue materialembeds at least part of said second porous layer (5).
 11. A flexibleabrasive member according to claim 9, wherein said layer (8) of gluematerial is bonded to at least one of said second porous layer (5) andsaid layer (4) of filling material and said metal deposits (2).